Filtration systems for aquarium tanks typically include filtering elements designed to provide various combinations of mechanical, chemical and biological filtration. These filtering elements are located within the aquarium tank itself or in a separate self-contained filter assembly usually mounted externally on the aquarium tank. Such externally mounted filter assembly has the advantage that it may be easily installed and its filtering elements easily removed, cleaned and replaced without unduly disturbing the fish within the aquarium tank. External filter assemblies suffer from the disadvantage that they require arrangements for priming the filter assembly. Any interruption or break in the water flow, such as may result from the removal and replacement of the filtering elements, can necessitate repriming of the system.
While the typically externally mounted filter assembly has been well developed in the industry, these filters can only provide a limited amount of filtration which satisfies for normal use. Occasionally, extra intense filtering of the aquarium tank is required. By way of example, when the aquarium water becomes cloudy as a result of inadequately washed sand or gravel placed in the tank, extra filtration is required. Similarly, as a result of the presence of a green color from algae in the tank, or as a result of the presence of fine dust particles, the normal external filter would be insufficient to clean the aquarium tank. These fine particles of contamination in the aquarium tank would tend to pass through the normal filtering elements in typical external filtering assemblies.
For such occasional extra filtration, it is typical to use a diatomaceous earth filter. Such filters are well known in the art and utilize a filter bag which must first be coated with the fine particles of diatomaceous earth filtration material. Once the bag is coated o primed with the diatomaceous earth, it can then be utilized in an external aquarium filtration system on a temporary basis for cleaning the aquarium tank of this contamination.
Diatomaceous earth filters have heretofore been known to be extremely clumsy and difficult to utilize. Typically, the filter bag is first primed externally of the filter and then placed into operation. Then a suction is created to cause the aquarium tank water to flow into the diatomaceous earth filter apparatus. By way of example, one such filter is described in U.S. Pat. No. 4,036,756 which requires the formation of a suction by means of a siphon in the diatomaceous earth filter before it can begin operation. Another arrangement of a diatomaceous earth filter is described in U.S. Pat. No. 4,490,250. This one, likewise, is a complex arrangement using a drive belt to drive the pump separate from the container holding the filter element. Additionally, every one of these filters must be hermetically sealed to prevent leakage.
In these, and other prior art systems, in addition to the difficulty in priming the filter bag causing it to be coated with the diatomaceous earth, there is an even greater problem in cleaning the filter. After the tank has been filtered, the diatomaceous earth filter must be turned off, which almost always causes a flow-back of some of the contaminated water from the filter back to the aquarium tank. Thereafter, disconnecting the filter from the tank, again causes a messy, sloppy, and difficult task.
The prior art diatomaceous earth filters are all of the type that stand on the floor or hang outside the aquarium tank and include large motors. They typically use jars, such as mason jars, which in use, must be hermetically sealed, require suction or a siphon to be created in order to operate, and are of the type that is difficult to utilize.
In addition, such diatomaceous earth filters are uniquely designed for that purpose and generally are not utilized for other filtration purposes. Accordingly, it is necessary to have a separate diatomaceous earth filter which must be utilized on an intermittent basis in addition to the separate filtration system used in normal operation.